This paper develops the concept of “strategic design”, the design implications of the interactions of a product with the whole user system, and relates it to other aspects of design. It describes some examples of poor strategic design that occur frequently, and some cases where effective strategic design has been important in the large-scale impact of an ambitious educational innovation. From these, the paper then seeks to infer some principles for strategic design. It is aimed at the three major constituencies of ISDDE: designers, design team leaders, and the client-funders that often commission their work. The hope is that sharpened awareness of the importance, and the challenges, of strategic design may help to increase the impact of good design as a whole.